Tooth marker of ecological abnormality: The interpretation of stress in extinct mega herbivores (proboscideans) of the Siwaliks of Pakistan

Abstract Climate affects living ecosystems and defines species physiology. Climate change causes certain stress on animals, recorded as Enamel Hypoplasia (EH). Proboscideans, the mega herbivores, were extensively represented in the Siwaliks of Pakistan between the Middle Miocene to Pleistocene (~15.99–~0.6 Ma). This study was carried out on 15 species from 9 genera and 4 families using 319 teeth from 266 individual quarries. Our results revealed that 20.06% (64/319) of teeth were infected by EH. Family Deinotheriidae faced higher stress during the terminal of the Middle Miocene (EH 25%). Dental characters of deinotheres indicated that this family preferred soft vegetation like C3 plants and failed to survive in grassland ecology at the onset of the Late Miocene (~10–9 Ma). Gomphotheriidae (EH 21.05%) and Stegodontidae (EH 23.40%) survived through warm and dry climatic conditions of the Late Miocene, but could not survive the cool and dry climate of Plio‐Pleistocene where grasslands were abundant with less browsing activity. Family Elephantidae (EH 8.47%) was successful in drier conditions and utilized the exclusive C4 diet in open grasslands as efficient grazers, indicated by their tooth morphology. Elephantids were dominant of the proboscideans in open grassland and drier climate during Plio‐Pleistocene in the Indian subcontinent. We assume that change in the Siwalik palaeoenvironment was governed by a microclimate.


| Palaeogeography of proboscidean
The Deinotheriids were characterized by the presence of vertically erupted all check teeth and downwardly pointed lower incisors (tusks). This is a monophyletic Siwalik group with only a single genus, Deinotherium (Sarwar, 1977). The genera Prodeinotherium Éhik, 1930, andAntoletherium Falconer, 1868 cannot be differentiated from Deinotherium. The taxonomic status of the genus is still controversial, and some authors (Tiwari et al., 2006) attributed the smaller sized animals as Prodeinotherium. However, the current study of EH is based only on two valid species of the genus Deinotherium; (i) D. pentapotamiae and (ii) D. indicum from the Siwaliks of Pakistan, given in Figure 1. These two species have overlapping temporal range, but they were different in body size, presence of tubercles, and very prominently developed talon ridge in M 2 (second molar) of D. indicum, whereas these characteristics were absent in D. pentapotamiae (Sahni & Tripathi, 1957). These dental assemblages belong to the Middle Miocene Siwaliks of Northern Pakistan (Sarwar, 1977).
The gomphotheres were the proboscideans known by their fossil record from all over the globe except from Antarctica and Australia from the Early Miocene to Late Pleistocene. By general appearance, they had two pairs of oppositely pointed upper and lower tusks (Lambert, 1992). They are characterized by the presence of trefoil shaped wear pattern (Prado & Alberdi, 2008). The earliest gom-   Barry et al. (2002) Nagri zone Nagri stage Nagri Formation Nagri Formation Gradstein et al. (2020) 11.63-9.0 Ma Barry et al. (2002) 3  Raza (1997) 18.3-14.3 Ma Johnson et al. (1982) and later on dispersed into Asia and Europe (Tassy, 1996). These proboscideans are characterized by 3 ̶ plated first two molars having three cusp pairs, and because of this character, these are known as trilophodonts. The evolution of the gomphotheres is considered to be the second radiation after the ancestral radiation of proboscideans. Molars of A. osborni are more progressive than A. sivalensis in shape (strongly oblique ridge-plates) and a number of ridge-plates (Sarwar, 1977). The palaeogeography of the Siwalik gomphotheres is given in Figure 2.
There is a debate on the taxonomical status of the stegodons, either they form a separate family or belong to Elephantidae (Saegusa et al., 2005;Shoshani & Tassy, 1996). This Siwalik clade consists of two genera, Stegodon and Stegolophodon, which are considered to have evolved from the Gomphotheriidae. The stegodons have low crowned teeth with many plate-like ridges in contrast to the high crowned plated molars of elephants and mammoths. In general, Stegolophodon has four tusks, two on each jaw, while Stegodon had only two straight tusks in the upper jaw. The earliest Stegolophodon fossils belong to the Middle Miocene of Thailand from there, the genus spread throughout the northern hemisphere, which may have happened in response to the Mid-Miocene climatic warming (Saegusa, 1996). Stegodon is assumed to have originated from Stegolophodon in South China during the Early Pliocene because of the higher number and diversity in this region. Stegodon remains were also reported from Kenya, and Africa dated back to 6.5 million years (Saegusa, 1996). Stegodon has also been known from Japan with several endemic species (Saegusa et al., 2005 Only the lectotype fits to S. bombifrons. Some former palaeontologists (Hooijer, 1955;Lydekker, 1876;Osborn, 1942) have proposed that S. ganesa is the junior synonym of S. insignis, regardless of the fact that both species have considerable differences in the cranial morphology.
On the basis of both sexual dimorphism and ontogenetic changes in cranial features, S. insignis and S. ganesa are particularly dissimilar (Abbas et al., 2019), contrary to some previous authors, claimed as a single collective species (Chauhan, 2008). We concluded that S. insignis and S. ganesa are not a single collective species (Saegusa, 1987). The palaeogeography of the Siwalik Stegodontids is given in Figure 3.

F I G U R E 2
The stratigraphic range of genera of the family Gomphotheriidae in the Siwaliks of Pakistan (Abbas et al., 2018;Behrensmeyer & Barry, 2005

| Enamel Hypoplasia
Enamel, the whitish casing of the tooth crowns, is highly mineralized and the most durable tissue in the mammalian body (Kierdorf et al., 2012;Shawashy & Yaeger, 1986). Enamel Hypoplasia (EH) is a deficit in tooth enamel due to the physiological offenses that cripple ameloblasts deposition during the secretory phase of amelogenesis (Guita, 1984;Sarnat & Schour, 1941;Shafer et al., 1983;Yaeger, 1966). The ameloblasts, tissues which make enamel, may describe its great degree of sensitivity to physiological perturbations. The EH is ensured when the stress intensity reaches a certain threshold level, and if the ameloblasts are active at that time of physiological stress, then the ameloblasts can function no longer. This stress threshold may be passed in the chronic or episodic manner (Goodman & Rose, 1990). However, EH is a permanent failure of tooth enamel ( Figure 5) to attain its normal thickness during the development of the tooth crown (Goodman et al., 1987;Goodman & Rose, 1991). The anomaly may appear as a horizontal or vertical groove more or less encircling the tooth crown or as discrete "pin prick" sized cavities in the ordinary enamel figure, presumed to correspond to less severe stress (Ainamo et al., 1982). It can be associated with a myriad of causes but is generally linked to malnutrition, infections, or febrile disease (Suckling, 1989).
Tooth enamel, in this regard, is unique because of its inability to remodel. On the basis of ease of enamel examination, sensitivity, failure to remodel, and a chronological array of its developmental pattern, it can be the perfect tissue for recording alterations in an animal physiology during its tooth development (Kreshover, 1940;Massler et al., 1941;Sarnat & Schour, 1941). The EH in fossilized teeth has a potential of providing a perspective into the ecological conditions of an extinct animal's life. The presence of EH in fossilized teeth has been recently unveiled by many paleontologists (Ahmad et al., 2018;Barrón-Ortiz et al., 2019;Bohmer & Rossner, 2017;Byerly, 2007;Mead, 1999;Odendaal et al., 2003Odendaal et al., , 2004Roohi et al., 2015), added additional and much reliable evidence to propose the palaeoclimatic fluctuations on a regional scale.
The beauty of the present framework is the application of EH and selection of such specific taxon of vertebrate mammals (Proboscidea) whose fossil assemblages cover the whole chronolog-  (Osborn, 1942;Saegusa, 1987;Saegusa et al., 2005;Tassy, 1983).

F I G U R E 4
The stratigraphic range of different members of the family Elephantidae in the Siwaliks of Pakistan (Agarwal et al., 1993;Dennell et al., 2006;Hussain et al., 1992;Nanda, 1997

| Identification of specimens
The dental terminology of Tassy (1996) and Harris (1976) was used to identify proboscidean tooth remains. Some old samples with unsettled or disputed taxonomy were also adjusted in the suitable groups with the help of Sarwar (1977), Tassy (1996, 2005), and the unpublished PhD thesis of Dr. Syed Ghyour Abbas et al. (2018).
Before the analysis of EH, fossil remains were first scrutinized as "readable" or "unreadable" teeth, and only the readable teeth were used. Teeth were considered unreadable because: (i) extremely fragmented or worn enamel; (ii) being completely covered with dental calculus or cementum; (iii) or their enamel surfaces were impossible to examine, because they were erupting or concealed in the alveolus. Teeth with any of the completely readable sides were recorded.
All types of check teeth were included.

| Preparation of specimens
The readable dental material was assembled, if broken at some parts, washed, and cleaned before the examination. The specimens whose catalog numbers were vague or wiped out were also included by giving them a new catalog number serially starting from its family alphabet name. For example, a specimen with an erased catalog number, i.e., Anancus sivalensis, a member of the family Gomphotheriidae, was written as "PUPC-G 1 " and so on serially.
The EH analyses were accomplished macroscopically following the methods outlined by Goodman and Rose (1990) and Lukacs (1989Lukacs ( , 1999. Different laboratory equipment and scientific instruments were used for the examination and recording of EH as; (i) Digital Vernier Caliper with 100 mm measuring capacity.
(ii) Digital handheld HDR camera for photography.
(iii) Large dissecting trays with cotton bed to shift the samples.

F I G U R E 5
Longitudinal cross section of mammalian (proboscidean) tooth for the development of enamel and dentine, a diagrammatical representation of the formation of EH.
(iv) A 60-100 Watt incandescent light, with variable power, was used for laboratory examination of samples.
(v) A 10× hand held lens was used for magnification, identification, precision, and confirmation of EH.
Each specimen was judged with a 10× hand lens after the examination with the naked eye to rectify the presence or absence of EH. Berti and Mahaney (1995) and Hillson and Bond (1997) also defined that the analyses of EH requa ire detailed examination of each tooth surface under magnifications.

| Scoring of Enamel Hypoplasia
During the examination, the position of EH was recorded, starting from root crown junction (RCJ) to enamel defect. The distance was measured to the center of the enamel defect. For each enamel defect, the distance indicated the timing of EH formation. Only labial and lingual surfaces of tooth crowns were contemplated for the occurrences of EH, and only the mandibular and maxillary teeth were

| Collective evaluates of EH by two raters
Firstly, two different light sources (sunlight and 60-100 watt incandescent light with variable settings) were used, and the specimens were oriented obliquely, when entailed to the artificial light source following Lukacs (1989Lukacs ( , 1999. Several times a variable amount of light appeared greatly useful for individual samples to identify either EH was present or not. The orientation of specimens really matters because EH is sometimes masked by the mirrored light or by the color of the specimen, which shades the tooth anomaly. The analysis was accomplished duly by two observers to create more objective results following Guatelli-Steinberg (2003).
The repeatability and reliability is an indispensable exercise during the examination of EH, especially in proboscidean teeth, because of enamel rugosity and the presence of perikymata. The guidelines by Landis and Koch (1977) were followed for the interpretation of Kappa. Cohen (1960) "Kappa" statistics was run for the explanation of agreement or disagreement between two observers. The calculations of the "K" value indicate the inter-rater reliability between the observers. The values of "p" indicate the precision and validity of results, whether the difference in opinion between the two raters is significant or not. Chi-square test was also performed for paired comparisons. In pursuit of multiple comparisons of EH between each of the families and genera, the Mann-Whitney U test, was run after the Kruskal-Wallis test where the comparisons of significant level (p-value) for the occurrence of EH within 4 families and 9 genera were individually calculated.  Table 3 delivers detailed information on the occurrence of EH at the taxon level. Figure 6 imparts the pictographic representation of some representative tooth specimens of the Siwalik proboscideans showing EH.

| EH prevalence in Deinotheriids
The results for the frequency of EH by tooth are summarized in

| EH prevalence in Gomphotheres
The results for the frequency of EH by tooth are summarized in

| EH prevalence in Stegodontids
The present analysis of the family Stegodontidae consisted of 94 teeth examined for the occurrence of EH. Twenty two teeth out of 94 revealed almost 23.40% of EH.

| EH prevalence in Elephantids
The current analysis consisted of 5 defected teeth out of 59 of the showed 11.11% of EH anomaly with only 1 defected teeth out of 9 (Table 3).

| An inter-rater reliability: interpretation of Kappa
The data from two individual raters were compared to check the

| Comparison of stress between families and genera
The comparison for the occurrence of frequency of EH between all the 4 Siwalik families, as well as 9 genera of the Order Proboscidea, included in this framework, was analyzed statistically. The normality of the data is checked by the Shapiro-Wilk test. Here the p-values (<.05) revealed that the data was nonparametric. So, the data was  Table 4. Similarly, the detail of comparisons at the generic level is also given below in Table 5.

| DISCUSS ION
Enamel hypoplasia observed in proboscideans depends on the developmental timings of tooth crowns in these animals. Modern proboscideans lack permanent cheek teeth, which succeed one another by an unusual horizontal tooth displacement mechanism. This mechanism occurs only in elephanti-morph proboscideans (gomphotheres, Stegodontids, Mammoths, and Elephants). Horizontal tooth displacement provides elephanti-morphs with an adaptive advantage over primitive proboscideans (Deinotheriids) with vertical tooth replacement (Sanders, 2017). This study included all the linear defects manifested as thin bands of defective enamel, which unlikely seem to be a general nutritional stress. This chapter emphasizes the occurrence of the anomaly (EH) and its correlation to the fluctuating palaeoecological conditions and vegetational patterns, linked to the movement of proboscideans out of the Siwaliks.

| Comparison of EH in the family Deinotheriidae
The Deinotheriids represent different morphological traits as com-  (Karp et al., 2018). The Deinotheriids were the most affected animals compared to other browsers as they are almost fully reliant on C 3 vegetation at that time. The diversity of many artiodactyls also decreased after 13 Ma ago (Barry et al., 1995) at the terminal of the Middle Miocene near the Late Miocene.
The changing climatic conditions may limit the niche and diet, and cause more competition between species the of same as well as in different taxa with similar diets, leading to an increase in the likelihood of exclusion (Behrensmeyer & Barry, 2005 (Harris, 1975;Huttunen, 2002aHuttunen, , 2002b. The stress pattern may also be indicative of increased competition with contemporary mammals. Multiple proxies have already been utilized for the assessment of the diet and ecology of animals. The dental characters, craniometrics, stable isotope analysis, mesowear analysis, and tusk orientation indicated a browsing behavior of the Deinotheriids under a semi closed forestland habitat (Cerling et al., 1999;Cerling et al., 2015;Sarwar, 1977). As the stress was somehow greater in D. pentapotamiae, they disappeared earlier than D. indicum, perhaps their shorter body size and failure to compete with contemporary herbivores.
The post-Sivapithecus interval marks the extinction of many forests inhabiting species therefore, we can assume that the localized extinction of Deinotheriids was also occurred in this interval. The Deinotheriids from Africa and India (Patnaik et al., 2019) also were dominant browsers and preferred the shady trees under an annual rainfall regime (Cerling et al., 1993;Nelson, 2005).  Raza et al. (1984).
The climate consistency decreased substantially after 13 Ma, on the basis of δ 18 O amplitudes, but there was remarkable warming environmental conditions at 10.8 Ma (Holbourn et al., 2013). The Siwalik record imply a reduction of annual rainfall with a change in seasonality of precipitation between savannah (C 4 grasses) and dry woodlands and monsoon forest (C 3 ) was maintained by a small differences during Late Miocene (Badgley et al., 2008). However, the disappearance of the genus and one of its diet competitors, Listriodon pentapotamiae, indicate somewhat short but severe environmental changes in the Siwalik region at the terminal of the middle Miocene.
The presence of the Deinotherium in the Late Miocene of Europe (Haiduc et al., 2018;Van der Made et al., 2006) and even the Pleistocene of Africa (Fernandez & Vrba, 2006;Geraads, 2010;Maclnnes, 1942) is the one hypothesis that supports the dispersal and migration of this taxon from the Siwalik because of massive environmental change locally. Hence, it can be proposed that 10.8 Ma approx. Was a time of considerable change in regional climate that may have caused reduction in suitable habitats for Deinotheriidae, which have increased the likelihood of migration/extinction of the genus along with many other reasons from the Siwaliks of Pakistan.

Gomphotheriidae (published data, included only for comaprisons)
The results of EH from the family Gomphotheriidae allow us to trace the palaeoecological conditions of the Siwaliks. Gomphotherium the Late Miocene-Pliocene boundary (Hynek et al., 2012). Miocene-Pliocene was also a tectonic stress event (Sperber et al., 1989) along with vegetational change towards the expansion of grasslands and intensified global cooling (Behrensmeyer et al., 2007;Liu & Jacques, 2010). The episodes of monsoon intensification were also determined by Sanyal et al. (2004). Despite of increased hypsodonty in the taxon over time, this species failed to compete with more dedicated grazers like bovids during the expansion of C 4 grasslands.

TA B L E 5 p-Value comparison
In Asia, the first records of the anancine gomphotheres are represented by A. perimensis from the Potwar Plateau, Pakistan, and Perim Island, India. From Pakistan, A. perimensis is documented from the Dhok Pathan Formation (DPF) dated back between 9.8 and ∼3.5 Ma Tassy, 1983). Anancus are reported from 8.6-8.1 Ma Patnaik, 2013). Tobien (1978) and Tassy (1983) developed its correlation to the DPF, whereas Pickford and Pourabrishami (2013) (Head et al., 2008). The average global long term ice volume increased between 1.25 Ma and 700 ka associated with Major cooling phases (Clark et al., 2006). The mass death of these proboscideans was also reported by Asevedo et al. (2012) during the Pleistocene because of extended periods of low humidity with mixed oak forests of a dry climate dominated by open vegetation (Ravazzi & Strick, 1995). These very unstable ecological conditions, which started to occur in the Early Pleistocene, followed by substantial glaciation with ice sheaths and cooling regimes during

| Comparison of EH in the family Stegodontidae
The detail of the occurrence of EH was given in Table 2 (Schuster et al., 2006) and the radiation of some succulent plant lineages (Arakaki et al., 2011). This modification in vegetational pattern is because of long term monsoonal changes in the Siwalik sub-region during Late Miocene and natural disasters as well. The expansion of savannas replacing the tropical and subtropical forests is a characteristic of the Late Miocene (Cerling, Harris, Ambrose, et al., 1997;Cerling, Harris, MacFadden, et al., 1997). The Late Miocene of

Himalayas foreland shifts from dominant vegetation of shrubs and
trees towards open C 4 grasslands with a long term climatic drying after 7.7 Ma ago (Clift et al., 2020;DeMiguel et al., 2019;Merceron et al., 2004). This drying is also closely linked to global cooling (Liu & Jacques, 2010). A rapid radiation and diversification was reported by Arakaki et al. (2011), first during 8-6 Ma, at Late Miocene times and the second at 3-2.5 Ma of Plio-Pleistocene times.
S. insignis with very low magnitude (15.79%) of EH revealed that the Pliocene environmental conditions were slightly more stable than the previous epochs. The supposition got more strength by the recurrence of Deinotherium fossils (almost purely browsers) from the Pliocene of India (Colbert, 1935). Highly increased magnitude of EH in S. ganesa (33.33%) revealed that the Pleistocene of the Siwaliks (2.58-0.6 Ma) had very unstable palaeoenvironmental conditions with much dominant C 4 environment and cooling episodes (Clark et al., 2006;Head et al., 2008;Ravazzi & Strick, 1995;Smith & DeSantis, 2020). The conditions were unsuitable for S. ganesa, the latest survivors of the family Stegodontidae, profoundly feeding on C 3 plants. Morgan (1973)

| Comparison of EH in the family Elephantidae
The analyzed material of the family Elephantidae ranges from the Pliocene to the Middle Pleistocene of the Siwaliks. Many researchers (Barry et al., 1982;Barry et al., 2002;Dennell et al., 2006;Hussain et al., 1992;Nanda, 1997;Shah, 2009) estimated the range zone of Elephas in the Siwaliks of Pakistan as 2.9-1.5 Ma for E. planifrons and 2.7-0.6 Ma for E. hysudricus (Hussain et al., 1992;Nanda, 1997 (Damuth et al., 2002;Eronen et al., 2010;Janis, 1993;Kaiser et al., 2013;Patnaik, 2015;Patnaik et al., 2019;Roohi et al., 2015). The studies indicate that the Pleistocene elephants (immigrants into the Siwaliks) were pure C 4 grazers. These elephants can be considered among the earliest large mammals who adapted purely towards the C 4 vegetational type along with equids (Polissar et al., 2019;Quade et al., 1992). The Late Pleistocene was the time of great climatic variations with less humid to colder and drier environments accompanied by prevailing ice sheaths (Clark et al., 2006;Head et al., 2008;Ravazzi & Strick, 1995;Smith & DeSantis, 2020). The comparison of present results of EH in Proboscidea with previously published data on the other Siwalik mammals is given in following Figure 7. The occurrence of EH in different Siwalik mammal families indicate that the ecological stress is supposed to be a major contributor for the evolution and migration of many taxa from the Siwalik sub-region. Similarly, the Figure 8 also indicated that the animal taxa, with less stress, survived longer by the evolution of more advanced dental and morphological characters in the Siwaliks compared to the others. The current results suggest that the elephantids were not extinct from the Siwaliks but evolved to the present Asiatic genus "Elephas" still present in the Indian subcontinent (E. maximus).

| P OTENTIAL LIMITATI ON S OF MICROTOMOG R APHY
Microtomography is used to obtain a high resolution of a physical object without destroying the original object that can't be obtained by any other nondestructive technology. It can be used to study the interior structure of the tooth and other biological samples without having to cut the samples, preserving the samples or specimens for future studies.
Actually, I didn't find the facility of Microtomography for such type of study anywhere in Pakistan yet. The facility is only available in hospitals for disease diagnostics, but they didn't agree to run it on our samples scanning due to possible contamination of the instruments. In addition, sending samples to foreign countries for analysis is also very laborious, expensive, and difficult due to COVID. Hence, I will keep trying to find out, but it still looks impossible at this point.
I would try my best to use this technique in future work.

| CON CLUS IONS
The current analysis allowed us to estimate that the Siwalik proboscideans preferred moist and warm climatic regimes with predominantly a browsing habitat similar to their ancestors, as proposed by Liu et al. (2008) for Barytherium and Moeritherium in Fayum, Egypt.
The frequency of EH is linked to the changes in ecological conditions related to the vegetational pattern and competition with other herbivore communities of an area between the Middle Miocene and to Pleistocene of the Siwaliks.
As enamel hypoplasia primarily reflects episodes of systemic stress which can weaken the immune system of animals, reduced F I G U R E 7 Comparison of the occurrence of stress as EH in the studied Siwalik mammalian families. Giraffidae and Tragulidae (Ahmad et al., 2018(Ahmad et al., , 2020, Rhinocerotidae (Roohi et al., 2015).
fitness, and cause failure to survival, causes mortality at a big scale during younger ages (Temple, 2014), supposed to be a one of many contributing factors to increase the likelihood of extinction (Barrón-Ortiz et al., 2019). Proboscideans are social animals (Hacker et al., 2015). Sociality can include increased feeding competition (Silk, 2007), greater likelihood of disease transmission (Gompper, 1996), loss of reproductive fitness (Armitage, 1999), intra-species aggression (Whitehead, 1997), and increased detection by predators or prey (Beck et al., 2012). This hypothesis supports that proboscideans experienced increased levels of systemic physiological, ecological, predatory, and competitive stress, which can be linked to the reduced dietary resources, specifically during the Late Miocene and Pleistocene times. This enhanced competition for survival triggered the likelihood of complete migration of these herbivore animal taxa from the Siwaliks. These constraints were more pronounced during the Latest Miocene and Pleistocene times. We believe that for a better understanding of the dietary regime utilized by the proboscideans, a comprehensive microwear and mesowear, along with stable isotopic analyses from proboscidean tooth enamel, is further required in the future.
F I G U R E 8 Genus level comparison of the Siwalik stress events on different proboscideans, each color indicates a different family (green = Deinotheriidae, red = Gomphotheriidae, yellow = Stegodontidae, blue = Elephantidae); length of the color bars indicate the frequency of environmental stress during different time intervals of the Siwaliks palaeoenvironment (Barry et al., 2002;Barry & Flynn, 1990;Dennell et al., 2006).

ACK N OWLED G M ENTS
The authors are very thankful to Dr. Abdul Majid Khan for his support and guidance. Moreover, the authors are also thankful to John Lukacs (Professor Emeritus, University of Oregon, USA) for his valuable suggestions about the "Kappa" statistic, which proved to be highly significant in improving this article.

CO N FLI C T O F I NTE R E S T
The authors declare no conflict of interest in this study.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data used in this article come from PhD dissertation of one of us (Dr. Muhammad Ameen), which will be available at: https://doi.